Intent to ship: CSS conic-gradient

[Tim Nguyen]

Summary: CSS conic-gradients allow developers to specify gradients that
start from a certain angle where color stops are placed around the
circumference of a circle centered around a specified point.

Thanks to my friend Mohamed's work on Direct2D
<https://bugzilla.mozilla.org/show_bug.cgi?id=1617396>, full Windows
support is now available, so this can now be enabled by default everywhere.

Bug: https://bugzilla.mozilla.org/show_bug.cgi?id=conic-gradients

Standard: https://drafts.csswg.org/css-images-4/#conic-gradients

Target Release: 83

Platform coverage: All, but printing support will arrive after Cairo support
<https://bugzilla.mozilla.org/show_bug.cgi?id=1617039>.

Preference for feature: On by default (layout.css.conic-gradient.enabled)

DevTools bug:

- Output parser support (angle/color swatches) was done in bug 1621794
<https://bugzilla.mozilla.org/show_bug.cgi?id=1621794>
- CSS autocomplete works
- Prototype for a linear-gradient visualizer was done in bug 1364380
<https://bugzilla.mozilla.org/show_bug.cgi?id=1364380> as pointed out by
Patrick in the last email thread

Other browsers: shipped since Chrome 69, Safari 12.1, Edge 79 and Opera 64

web-platform-tests:
https://searchfox.org/mozilla-central/search?q=conic-gradient&case=false&regexp=false&path=testing%2Fweb-platform
Many parsing tests along with few rendering tests were already there,
although many were added at the beginning of the year in bug 1616986
<https://bugzilla.mozilla.org/show_bug.cgi?id=1616986>.

Restricted to secure contexts: No, CSS features are usually not restricted
to secure contexts

Is this feature enabled by default in sandboxed iframes? Yes

[Sean Voisen]

On Fri, Oct 9, 2020 at 12:13 PM Tim Nguyen <ntim...@gmail.com> wrote:

> Summary: CSS conic-gradients allow developers to specify gradients that
> start from a certain angle where color stops are placed around the
> circumference of a circle centered around a specified point.
>
> Thanks to my friend Mohamed's work on Direct2D
> <https://bugzilla.mozilla.org/show_bug.cgi?id=1617396>, full Windows
> support is now available, so this can now be enabled by default everywhere.
>

A pleasant surprise! Thank you Tim and Mohamed for your hard work getting
this feature ready to ship!

Platform coverage: All, but printing support will arrive after Cairo support
> <https://bugzilla.mozilla.org/show_bug.cgi?id=1617039>.
>

I suspect not many people are printing conic-gradients, but it would be
nice to have this as part of shipping. Or, at the very least, ensure the
print preview does not incorrectly represent the output. I guess that's
this: https://bugzilla.mozilla.org/show_bug.cgi?id=1670287

Cheers,
Sean